The invention relates to the field of fuel cells and it addresses more particularly the problem of safety to be observed during startup or stopping phases of a cell using as its gaseous fluid hydrogen and air.
In cells of the above type, it is known that it is desirable to maintain and stabilize conditions of supply of the anode and cathode circuits, such that in no case can there be produced, between the hydrogen and the oxygen of the air, an explosive mixture which can be the cause of incidents, or even serious accidents.
However, such a risk can be considered as potential during operation of starting or placing in service when the supply circuit for hydrogen for the anode compartments is located, for reasons of previous use or non-use, at least in part filled with air.
Such is also the case during stopping a fuel cell, given that the drop in pressure which takes place in the anode compartment or compartments by the consumption of hydrogen, the cooling which takes place and the condensation of water, can be the cause of untimely entry of air adapted to give rise, with the residual hydrogen, to an explosive mixture.
These two possibilities are taken in consideration and generally give rise to steps of inerting the anode compartment or compartments by injecting into this compartment or these compartments a neutral gas which can be stored and rendered available as desired.
The automatic control installation of a fuel cell is thus more complicated, more cumbersome and more in need of verification, control and maintenance.
Taking into consideration these requirements leads one objectively to consider whether it is possible to be able to overcome the drawback mentioned above whilst responding positively to the problem of safety, by simplifying the technical means necessary to proceed to shutting down the anode compartment or compartments.
It is thus the object of the invention to propose a new process and new device such that the installation itself of the fuel cell will be able to ensure, by technical, simple, robust reliable and less costly means, a self-shutting down of the anode compartment of the element or elements or cells by an uncomplicated control process which can be used by personnel even who are not specially qualified.
To achieve the above object, the process of the invention is characterized in that, to ensure the start-up of a fuel cell,
the hydrogen circuit of the anode compartment or compartments is progressively opened to cause air that may be included to circulate to said compartment in contact with the catalyst of the anode and to cause the formation of water and the production of a neutral gaseous mixture
simultaneously, the pressure of said neutral gaseous mixture is measured and the complete opening of the hydrogen circuit is ensured after a predetermined time,
then the nominal hydrogen pressure is stabilized in the anode compartment,
then the air supply circuit of the cathode compartment is opened, so as to establish stabilized operating conditions.
The invention also has for its object a device designed to practice the processes described above, and adapted for safety during startup of a fuel cell comprising at least one element comprising an anode compartment and a cathode compartment connected, for the anode, to a hydrogen circulation circuit and, for the cathode, to an air circulation circuit, this device comprising:
two valves disposed respectively in the inlet and the outlet of the hydrogen circuit of the anode compartment,
at least the valve disposed in the inlet of the hydrogen circuit being progressively controlled.